National Park in Krabi. It is the Shell Cemetery 10 minutes car drive outside Krabi. It is also called Fossil Beach with rock formation dating 75 million years old.
Apparently, there are only three of these beaches/places in the world: Chicago (USA), Japan and Thailand. Very cool despite the low tide.
But I would not pay 200 baht for it. I got in for 40 baht (Thai price) with my Thai husband and Thai kids and thanks to my registration book stating I live in Thailand.